This investigation is designed to achieve a greater understanding of the chemistry of technetium and to use this knowledge in the rational design of new radiopharmaceuticals labeled with Tc-99m for future use in clinical nuclear medicine. Beginning with known compounds in well defined oxidation states, complexes will be prepared, isolated and studied using methods which have been successfully applied to the coordination chemistry of other transition metals. The aim of the synthetic program is to provide a profile of the oxidation state, stereochemistry, nature of the bonding and relative ligand affinities of technetium compounds. As the systematics of the element's behavior emerge, this information will be used to formulate and synthesize compounds which show potential as radioactive diagnostic agents. These will then be evaluated as such in appropriate animal models.